Conventionally, all solid state batteries are known as secondary batteries which are excellent in reliability and safety. For example, Patent Document 1 discloses an all solid state battery that has an electrolyte film composed of a NaSICON-type film. In addition, Patent Document 2 discloses a lithium ion conductive solid electrolyte represented by the chemical formula Li1+xMxZr2−x(PO4)3. In the formula, M represents at least one element selected from Al and rare-earth elements, and x represents 0.1 to 1.9.
Patent Document 1: Published Japanese Translation of PCT International Application No. 2013-510391
Patent Document 2: Japanese Patent Application Laid-Open No. 2-250264